Thank you so much for your reply. I guess I got confused before, bc restoring the data dir to get the old seed makes perfect sense!
I restored my wallet by temporarily restoring the data dir. The wallet then took a little while to sync all the addresses. Unfortunately, the balance displays zero.
I made meticulous records of all the accounting from Bisq, and my records ALSO show the BTC amount that was previously displayed in the Available Balance but not lockable in offers should be in the wallet’s addresses.
Do you have any idea what my next step is? I find it highly unlikely that Bisq simply had a bug displaying too high of an Available Balance before, since my accounting records kept outside Bisq also show that there should be this extra BTC still available.